feat(robo): expose function to trigger build

[Pkmmte]

Robos are already able to be started via Robo.start() but this doesn’t build them. You still have to call the Robo CLI to do so.

We should expose something like Robo.build() which directly calls the CLI handler for this. That means we should not take a shortcut by calling exec and executing robo build. For now, let’s not worry about plugin builds.

Use case

Incremental Robo adoption w/ auto builds.

Now that Robo.js is capable of more than just Discord bots thanks to the API plugin, we can start using it to create API servers. I’m actually already using it this way for one internal project, but there’s several other existing projects that could benefit from it. However, it’s overkill to do an entire rewrite at once, especially for larger ones.

This would allow the usage of Robo as an API server incrementally by letting custom entry points build on their own prior to starting, enabling a seamless auto restart experience.